Updated support for getReplica

The parsing of the arguments should probably be refactored
into a helper function.

Change-Id: I3e2dafeb7a6d10901d828eb9c8890c18796b815b
Reviewed-on: http://review.couchbase.org/27364
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>